Advocates say the coronavirus pandemic has contributed to the increase, with Lt. Gov. Susan Bysiewicz calling it an "epidemic within an epidemic."
The pandemic has "just exacerbated" the overdose epidemic "by the isolation and the stress on families," Bysiewicz said.
Gov. Ned Lamont declared Monday as Overdose Awareness Day in the state and ordered the U.S. and state flags lowered to half staff to honor those who've died.
RELATED: 'Protect Our Children: The Opioid Crisis' - Watch it here on ABC7NY
"Addiction is an illness that should be treated just as any other public health emergency, and we cannot allow this epidemic to continue consuming our families and residents," Lamont said in a statement. "We need to send the message that this disorder can no longer hide in the shadows and be treated like something that shouldn't be discussed."
The governor said there are many resources available for people seeking treatment for drug addiction and families seeking support. Information is available at www.liveloud.org and 800-563-4086.
Nearly 650 people in Connecticut died of unintentional drug overdoses from January to June, an 18% increase over the same period last year, according to the state Department of Public Health. Overdose deaths are on track to surpass last year's total of 1,200. Nearly 87% of all overdose deaths this year have been linked to the powerful opioid fentanyl.
Democratic U.S. Sen. Richard Blumenthal said he plans to urge his colleagues in the U.S. Senate to pass the HEROES Act, which includes $3 billion for substance abuse services across the U.S. He called it his top priority, noting the pandemic has isolated people and enhanced "the triggers to substance abuse" while making it harder to access services and rely on family and employment.
ALSO READ: Dinner and a movie - indoor dining, movie theaters reopening in NJ
Hundreds of nursing homes still aren't allowing visitation amid coronavirus pandemic
Hundreds of nursing homes still aren't allowing visitation
MORE CORONAVIRUS COVID-19 COVERAGE
How coronavirus changed the New York region
Do you have coronavirus symptoms?
What's Open, What's Closed in the Tri-State area
Back to school information
COVID-19 Help, Information. Stimulus and Business Updates
UPDATES
New York City
New Jersey
Long Island
Westchester and Hudson Valley
Connecticut
abc7NY Phase Tracker: